1. Field of the Invention
The present invention relates to an extramedullary fluoroscopic alignment guide for use in joint replacement surgery. The fluoroscopic alignment guide of the present invention may be particularly useful in less-invasive surgical procedures, such as in unicompartmental knee replacement. The present invention also relates to a surgical method for resection of a bone, and may be particularly useful in resecting a tibia for knee arthroplasty.
2. Description of the Prior Art
The surgical preparation of bone endings for receiving prosthetic joints for either a total or partial joint replacement is a complex procedure. A number of bone cuts are made to effect the placement and orientation of the components of the prosthesis on the bone with the appropriate joint gaps in extension and flexion.
Considering, for example, modern knee arthroplasty, cuts are made at the distal end of the femur and proximal end of the tibia using alignment mechanisms and cutting guides. Accurate alignment of cutting guides and accurate implantation of the components of the knee prosthesis are paramount to long-term success of knee arthroplasty, both in the case of total knee arthroplasty and unicompartmental knee arthroplasty. Typically, the alignment guides are either intramedullary or extramedullary.
With intramedullary alignment guides, an intramedullary rod or similar device is placed intraoperatively in the medullary canal of the bone to be cut. Cuts to the bone are then referenced off of the intramedullary rod or off of some other device that is referenced off of a bone surface that has been cut in reference to the intramedullary rod.
With extramedullary alignment guides, an extramedullary rod or similar device is generally aligned along external landmarks to properly orient the system. For example, for resection of the proximal tibia, the extramedullary alignment guide is aligned from the center of the patient's knee to the center of the patient's ankle in a coronal plane in the medial-lateral direction. For tibial resection, the external landmarks used include the tibial tubercle, tibial spine, malleoli and foot in line with the mechanical axis of the tibia. In such procedures, the distal end of the extramedullary rod is generally affixed to the ankle through use of a clamp or similar device, such as a malleolar clamp that is positioned immediately proximal to the malleoli. A tibial resection guide is then affixed to the proximal end of the extramedullary rod. The extramedullary rod and clamping device remain external to the patient throughout the procedure. The lower assembly, comprising the clamp and the extramedullary rod, is translated in an anterior-posterior direction to align it parallel to the tibial axis. Medial-lateral alignment is adjusted to be approximately parallel to the tibial axis. Alignment of the assembly with the anatomical axis of the tibia results in proper alignment of the resection guide. The properly aligned resection guide may then be secured to the upper tibia using pins. Bone cuts may then be made to the tibia.
Refinements in topographical anatomy have resulted in a better understanding of the position of the ankle joint. Extramedullary guides are currently shifted medially at the ankle 3 to 5 mm depending on the girth of the ankle to accommodate the center of the talus. Proximal alignment of the extramedullary assembly is empirically centered between the tibial spines on the medial third of the tibial tubercle.
It is desirable that the cut to the proximal tibia, or other bone, be at a known, predetermined angle with respect to the mechanical axis of the tibia, or other bone, which in the case of the tibia, generally corresponds with the anatomical axis of the tibia. At present, there is some controversy as to whether the ultimate proximal tibial cut should be perpendicular to the tibial mechanical axis or at an angle of 3° of varus. Whichever angle is used, reproducible and accurate preparation of the upper tibia and placement of the tibial component of a knee prosthesis is extremely important for successful function and implant longevity. Proper alignment is perhaps more significant in the case of a unicompartmental or unicondylar tibial component of a knee prosthesis than in the case of a bicondylar tibial components, which are much more forgiving of malalignment than unicondylar knee prostheses. Proper alignment is also significant in the case of other joint replacement surgeries, such as in the case of shoulder prostheses and ankle prostheses.
Accordingly, to ensure that the cut made is optimal for proper alignment of the prosthetic implant with respect to an axis of the bone, it is important that the cutting guide be optimally aligned with respect to this axis of the bone. The present invention addresses the need for optimizing alignment of the surgical instruments prior to making a cut to the bone.
Reference is made to the following publications, which are incorporated by reference herein:
Teter, K. E. et al.: Accuracy of Intramedullary Versus Extramedullary Tibial Alignment Cutting Systems in Total Knee Arthroplasty. CORR 321: 106–110, 1995.
Sanders, R. et al.: Exposure of the Orthopaedic Surgeon to Radiation. JBJS 75-A: 326–330, 1993.
Evans, P. D. et al.: Radiological Study of the Accuracy of a Tibial Intramedullary Cutting Guide for Knee Arthroplasty. JOA 10: 43–46, 1995.
Dennis, D. A. et al.: Intramedullary Versus Extramedullary Tibial Alignment Systems in Total Knee Arthroplasty. JOA 8: 43–47, 1993.
Oswald, M. H. et al.: Radiological Analysis of Normal Axial Alignment of Femur and Tibia in View of Total Knee Arthroplasty. JOA 8: 419–426, 1993.
Lonner et al.: Effect of Rotation and Knee Flexion on Radiographic Alignment in Total Knee Arthroplasties. CORR 331: 102–106, 1996.
Perillo-Marcone, A. et al.: The Importance of Tibial Alignment, JOA 15: 1020–1027, 2000.
Cates, H. E. et al.: Intramedullary Versus Extramedullary Femoral Alignment Systems in Total Knee Replacement. CORR 286: 32–39, 1993.
Kennedy, W. R R. et al.: Unicompartmental Arthorplasty of the Knee. CORR 221: 278–285, 1987.
Bert, J. M. et al.: Universal Intramedullary Instrumentation for Unicompartmental Total Knee Arthroplasty. CORR 271: 79–87, 1991.
Reed, S. C. et al.: The Accuracy of Femoral Intramedullary Guides in Total Knee Arthroplasty. JOA 12: 677–682, 1997.
Thornhill, T. S. in Goldberg, V. M. Controversies of Total Knee Arthroplasty; Unicompartmental Total Knee Arthroplasty, 7–18, Raven Press, 1991.
Krackow, K. A. in Goldbery, V. M. Controversies of Total Knee Arthroplasty; Total Knee Arthroplasty: Techniques, 989–1005, Churchhill Livingstone, 1991.
Rosenberg, G. A. in Rand, J. A. Total Knee Arthroplasty; Surgical Technique of Posterior Cruciate Sacrificing, and Preserving Total Knee Arthroplasty, 115–153, Raven Press, 1993.
Marmor, L. in Rand, J. A. Total Knee Arthroplasty; Unicompartmental Knee Replacement, 245–180, Raven Press, 1993.
Scott, R. D. in Door, L. D. Techniques in Orthopaedics; Unicompartmental Knee Replacement; Robert Brigham Unicondylar Knee surgical technique, 1–23, Aspen Publication, April, 1990.
Symposia III: Unicompartmental TKR in the Millenium in the Knee Society/AAHKS Combined Specialty Day Meeting, AAOS, San Francisco, Calif. March 2001.
U.S. Pat. No. 6,036,696 (Lambrecht, et al., 2000) entitled “Guide-Pin Placement Device and Method of Use.”
U.S. Pat. No. 6,214,013 B1 (Lambrecht, et al., 2000) entitled “Method of Using a Guide-Pin Placement Device.”